1. Field of the Invention
This invention relates to the art of making tubular sleeves suitable for application to an assembled group of containers, such as glass bottles and the like, and more specifically to the method and apparatus for making a prescribed tubular plastic preform having unique physical properties. The tubular sleeve constitutes novel banding material and structure especially desirable for assemblying and heat-shrinking around the grouped containers so that the major exposed surfaces of such similar containers are held in tightly-constrained tangential relation.
2. Description of the Prior Art
It is common practice to merchandise many items such as containers for soft drinks, beer and the like, in packages containing a number of containers with the package normally including a handle or other hand-holding means to facilitate carrying the package. A most common package consists of a relatively-rigid paperboard blank formed around a group of containers, normally six or eight, with the folded blank usually being interlocked with itself and a plurality of similar containers in the package. The paperboard packages normally require partitions between individual containers, especially in the case of glass bottles, to avoid surface-to-surface contact. These paperboard blank packages have not been entirely satisfactory in that they are relatively expensive and are comparatively difficult to form, particularly with the high speeds required by modern filling, capping and packaging machines.
To overcome these and other deficiencies of the folded paperboard blank, cans have recently been packaged by assemblying the cans with a multi-apertured carrier formed from a sheet of resilient plastic material with the beaded end of the cans each being inserted through the apertures. The periphery of the apertures grasp the sidewalls of the cans and is locked beneath the bead securely enough to permit carrying of the package by a handle or finger holes formed in a central portion of the resilient plastic carrier. Heretofore, it has not been considered practical to package bottles in this manner because the elongated neck and shoulder portion projecting upwardly from the cylindrical body portion have made existing methods and apparatus for the retention of cans in a multi-pack impractical or unduly expensive for packaging bottles. Further, the relatively great distance over which the carrier must be moved in its application onto the body portion of the bottles has made it necessary to install the carrier on successive bottles substantially simultaneoulsy to avoid excessive distortion and tearing of the plastic carrier. Also, the side surfaces of bottles require additional retention means such as an encompassing band to avoid surface-to-surface impact of the bottles during handling, shipment and disassembly of the package. Such apparatus for packaging containers is disclosed in U.S. Pat. No. 3,509,684 to Hohl and Schribner, which patent is assigned to the same common assignee as the present patent application.
More recently, the introduction of shrinkable plastic overwraps has occurred causing drastic changes in the paperboard packages of the past. The following U.S. patents are representative of packages using plastic overwraps of various types. Most of these disclosures ae directed to various transparent film-type non-foamed shrink-wrap packages and to the use of prescribed handles, fingerholds and related supporting structures.
U.S. Pat. Nos. 3,532,214, 3,198,327, 3,552,559, 3,834,525, U.S. Pat. No. RE. 28,535, U.S. Pat. Nos. 3,650,394, 3,650,395, 3,817,373, 3,416,288, 3,747,749, 3,331,503, 3,302,784, 3,477,564, 3,756,397 and 3,217,874.
Multi-container packages which utilize transparent thermoplastic films are suitable for many applications; however, their use for packaging glass containers which contain light-sensitive comestibles such as beer is undesirable. Also such films do not provide the desired level of impact protection for a multi-pack of glass containers. Further, such films can be decorated with advertising information only with difficulty requiring the use of supplemental labels or wrappers for product identification.
The use of foamed polystyrene for shrink wrapping of multi-pack integral packages is disclosed in U.S. Pat. No. 3,400,810. However, the foamed polystyrene taught by this patent is biaxially oriented and will shrink generally uniformly in both directions. This type of overwrap in heat-shrunken condition exhibits generally the same strength properties in both directions, thus making expedient removal of the individual containers somewhat difficult. With this material, it is also difficult to form end seals of the flaps at the package ends due to both axial and circumferential shrinkage of the overwrap.